"Is it because I inherently possess only a human body?"
Demon Beasts have a long lifespan, which in fact is not so much related to how powerful their realms are.
It is more a result of the natural advantages inherent to their races.
Of course, the stronger the realm, the longer naturally one lives. Breaking through major realms also brings corresponding enhancements.
But at lower realms, the manifestation isn't as marked.
Luo Chen only obtained the corresponding physical strength and didn't experience a racial quality change, which is why his lifespan only increased by this amount.
Even say, unless he makes significant advancements in the path of Body Refinement, the enhancement to his lifespan won't be substantial.
After all, he's not practicing the traditional Body Refinement Technique developed by Human Cultivators that can increase lifespan.
When Luo Chen created that Cultivation Technique, it wasn't aimed at increasing lifespan anyway.
